Roasting High-Altitude Robusta: Profile Development for Cambodian Beans

High-altitude Robusta requires a different roasting approach than commodity Robusta — and also different from standard Arabica roasting protocols. For roasters sourcing OCC's Cambodian highland beans, understanding these differences is essential to delivering the quality the green bean is capable of.

**Why Robusta Roasts Differently**

Robusta's different chemical composition means it behaves differently in the drum:

* **Higher caffeine:** Caffeine has a higher melting point and affects how the bean absorbs heat

* **Higher chlorogenic acid concentration:** These break down during roasting — the timing of breakdown significantly affects bitterness in the final cup

* **Different first crack behavior:** Robusta's first crack is often less pronounced than Arabica's and occurs at slightly different temperatures

* **Different cellular structure:** Robusta beans are typically denser than their altitude-equivalent Arabica counterparts

**High-Altitude vs. Commercial Robusta Roasting**

The roasting protocols that work for commodity Robusta — often heavy dark roasting to mask defect flavors — are counterproductive for high-altitude specialty Robusta. OCC's beans have natural sweetness and complexity that needs to be developed, not obscured.

**Recommended Profile Development for OCC Mondulkiri**

*For filter/pour-over application:*

* Charge temperature: 180–190°C (drum roaster)

* Drying phase: 5–6 minutes, moderate airflow

* First crack: Target 195–200°C (will feel earlier and softer than Arabica)

* Development time: 2.5–3.5 minutes post-crack (15–20% of total roast time)

* Drop temperature: 205–210°C

* Total roast time: 10–12 minutes

*For espresso application:*

* Extend development phase by 30–45 seconds

* Higher drop temperature (215–220°C) for medium-dark development

* Rest 10–14 days before pulling shots

**Common Mistakes**

1. **Rushing development:** Insufficient post-crack development leaves raw, grassy notes

2. **Over-roasting:** Destroys the sweetness that differentiates high-altitude Robusta from commercial

3. **Applying Arabica timing:** Robusta's first crack behavior requires recalibration

**Cupping Protocol for Quality Control**

OCC recommends cupping against an SCA-adjacent Robusta protocol: slightly lower coffee-to-water ratio (1:17 rather than 1:15), brewed at 93°C, evaluated for body, sweetness, and finish rather than acidity-led scoring.

*→ The green bean potential is there. Your roast profile determines whether that potential reaches the cup.*